อยากได้ coed first day of week php .ใครพอมีบ้างครับ

function firstDayofWeek($week,$year) {
$timestamp = mktime(0, 0, 0, 1, 1, $year);
if( $week == 1 ) {
while ( date("W",$timestamp) < 2 ) {
$timestamp += (60*60*24);
}
$timestamp -= (60*60*24*8);
}
else {
while ( date("W",$timestamp) < $week ) {
$timestamp += (60*60*24);
}
$timestamp -= (60*60*24);
}
return $timestamp;
}